Lancet injector

ABSTRACT

A lancet injector is provided which has a tubular housing, a slidable lancet holder in the housing, a compression spring connected between the holder and one end of the housing, and a holder control member extending through a longitudinal slot in the sidewall of the housing. The control member is operable to move the lancet holder to a latched retracted position against the force of the spring, release the holder so that it moves linearly under the force of the spring and inertia to a skin piercing position and then back to a neutral position in which the spring is in a free length condition.

This is a continuation of application Ser. No. 278,024, filed June 29,1981, now abandoned.

DESCRIPTION

1. Technical Field

This invention relates to lancet injectors and more particularly to aninjector adapted for use with single-use or disposable lancets forobtaining blood samples for test purposes.

2. Background Art

Lancets generally have a handle and a needle extending from one end. Thelancet may be grasped between the thumb and index finger and made topierce the skin, for example, the skin of a patient's finger. The lancetis removed from the incision and blood from the finger transferred to ablood collection tube, such as a capillary tube or a pipette, forclinical testing. Some problems are associated with such a procedure.For example, the depth of penetration, the force employed in making theincision, and the angle of insertion and removal vary in accordance withthe person using the procedure. Also, the person or patient may be ableto view the lancet or procedure performed and this may be undesirable insome cases.

In attempting to overcome one or more of the above problems ordisadvantages, spring actuated lancet injector devices have been made,however, they have not been entirely satisfactory. For example, somehave been relatively complicated in construction and expensive to make.Some constructions require a plurality of springs and a relatively largenumber of elements for performing such functions as driving, latchingand retracting the lancet. Also, in some cases the lancet is in view andthis may add to the anxiety of the patient, especially where theincision is self-made, for example, when a diabetic makes blood glucosetests at home.

DISCLOSURE OF THE INVENTION

It is therefore an object of the present invention to provide animproved blood lancet injector which is relatively economical, simpleand effective in use, and which substantially overcomes one or more ofthe above problems.

In accordance with one aspect of the present invention, a lancet holderand a spring are disposed in a housing. An external control member isconnected to the holder to move the holder to a retracted positionagainst the force of the spring. The control member is movable torelease the holder to allow the holder to move to a lancet skin piercingposition and then to a withdrawn position. In another aspect, a singlespring is used.

These as well as other objects and advantages of the present inventionwill become more apparent from the following detailed description andaccompanying drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view of a lancet injector device in accordancewith a preferred embodiment of the invention;

FIG. 2 is a cross-sectional view of the injector device of FIG. 1;

FIG. 3 is an elevational view of an assembly of parts employed in theinjector device of FIG. 1;

FIG. 4 is a perspective view of the lancet of FIG. 1;

FIG. 5 is a fragmentary elevational view showing the upper portion ofthe injector device of FIG. 1 and illustrating the lancet in phantom inits skin piercing position, and the lancet and holder in the neutralposition; and

FIG. 6 is a fragmentary elevational view of the upper portion of theinjector device of FIG. 1 but showing the lancet holder in its lancetloading and unloading position with the lancet removed from the device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, and particularly to FIGS. 1 and 2, alancet injector 10 is shown including an elongate, generallycylindrical, housing 12 having a chamber or bore 14 and a lancet holder16 slidable in the housing bore 14. Housing 12 has a proximal end 18 inwhich is secured an end plug 20, and a distal end 22 covered by aremovable cap 24 having a central opening 25. Cap 24 is frictionallyheld in place by an annular bead 26 on the exterior of housing 12. Inthis way, the cap 24 can be snapped on and off the distal end 22 of thehousing.

The lancet holder 16, as also seen in FIG. 3, includes a generallycylindrical portion or slide 28 having a lancet holding member 30integrally connected to the distal end of the slide and a cylindricalextension or spring connector 32 at the proximal end of the slide. Aspring 34, shown as a coil spring, is disposed in the bore 14 betweenthe holder 16 and the plug 20. Spring 34 is shown engaged between theholder and a lower end portion of the housing. The connector 32 isprovided with a series of external integral bumps 36 disposed in aspiral arrangement for threadedly receiving and holding the upper ordistal end of coil spring 34. The spring 34 is threaded onto connector32 until the end of the spring engages an integral stop bump 38. The endplug 20 is shown provided with an integral extension or spring connector40 having a spiral series of integral bumps 42 which threadedly receivesand, as shown, holds the lower end of coil spring 34. The spring 34 isthreaded onto connector 40 until the end of the spring engages anintegral stop bump 44. If desired, the spring connectors 32 and 40 maybe provided with suitable screw threads instead of the series of bumpsor the ends of the spring 34 may be fixed to those connectors by othersuitable means.

The slide 28 has a hole 46 in which is secured a manual slide controlmember or control latch 48 which extends through a slot, indicatedgenerally at 50, in the sidewall of the housing 12. Latch 48 extends tothe exterior of the housing so that it provides an exterior manualcontrol movable along the slot 50 for positioning the lancet holder 16in a number of positions, as will be further described.

In assembling the device 10, the opposite ends of spring 34 may berespectively threaded onto connectors 32 and 40 to provide unitaryassembly, as seen in FIG. 3. This assembly can be inserted into theproximal end of the housing 12. The free length of the spring 34 is suchthat the unit may be manually rotated in the housing 12 by rotating plug20 until the hole 46 appears in the slot 50. The latch 48 may then beinserted through the slot and into hole 46. The latch 48 is fixed in thehole 46, for example, it may be adhesively connected or solvent bondedto the sidewalls of hole 46.

The holder 16 and connected latch 48 are preferably spring biased in acounterclockwise direction of rotation, as viewed in the drawings, thatis arcuately toward engagement with the left sidewall 52 of slot 50.This may be accomplished by providing the plug 20 and inner wall of thehousing 12 at its proximal end with cooperating surfaces which permitinsertion of the plug in a selected relative position with respect toslide 28. For example, as shown in FIG. 3, the plug 20 is provided witha plurality flats 54 which register with a plurality of flats 56 (FIG.2) on the inner sidewall of bore 14 at the proximal end 18. In this way,after the latch 48 is secured in hole 46, the plug 20 can be rotatedcounterclockwise so that the latch 48 engages a wall of slot 50, andthen the plug 20 is further rotated in the same direction a slightamount relative to holder 16, and then the plug is inserted into the end18 of the housing. Because of the cooperating flats 54 and 56, the plugcannot rotate and remains in its inserted position with the spring 34resiliently biasing the holder 16 and latch 48 leftwardly orcounterclockwise toward the left edge 52 of slot 50. The plug 20 may beadhesively connected such as by applying a suitable adhesive to the plugprior to insertion or a suitable solvent where the plug and housingmaterials can be solvent bonded.

The lancet holding member 30 is shown as a sleeve or cylindrical barrelhaving inner sidewalls 58 which frictionally engage outer peripheralsurfaces of a lancet 60. The lancet 60 is shown including a base orhandle 62, such as of plastic material, and a needle 64, such as a solidstainless steel pointed needle. The handle 62 may be molded about theneedle so that the tip of the needle extends outwardly beyond the upperend 66 of the handle. In FIG. 4, the lancet 60 is shown including anintegrally molded needle cap or sheath 68 covering the pointed needletip. The connection between the sheath 68 and the handle 62 is fragileso that by twisting or rotating the sheath relative to the handle, andthen pulling the sheath from the needle tip, the needle tip is exposed.The depth of the lancet holding member 30 is less than the length of thelancet handle 62 so that the upper portion, such as its upper one half,extends out of the holder and may be grapsed, for example, between thethumb and finger, for inserting the lancet 60 into the holder 30 and forremoving it after use. The bottom of the lancet bottoms on the bottom ofthe member 30 as shown in FIG. 2.

The slot 50, as best seen in FIGS. 1, 2 and 5, is shaped so as to have arelative wide portion at the proximal end of the slot through which thecontrol member 48 can be moved. In FIGS. 1 and 2, the member 48 is shownin its retracted position which places holder 16, member 30, and lancet60 in the retracted position with the needle tip wholly within thehousing 12. The control member 48 is shown releasably latched in anaxial recess 69 having a downward protrusion 70 for securely holding thelancet holder in the retracted position. When the lancet holder 30 is inthe retracted position, the spring 30 is in compression and exertingmaximum longitudinal or linear spring force on the holder 16 in thedistal direction. Also, the holder 16 is held in recess 69 against thebiasing force of spring 34.

When the control member 48 is manually unlatched from the retractedposition (FIGS. 1 and 2), such as by moving it leftward over theprotrusion 70 by applying pressure with a finger or thumb, the holder16, due to the force of spring 34 and inertia, moves swiftly linearly orlongitudinally and distally through housing bore 14 to a skin piercingposition wherein the point of needle 64 extends through opening 25 inthe end cap 24 and distally of the distal end of the housing as shown inphantom in FIG. 5. During this movement control member 48 moves along aslot portion 72. The holder 16 and lancet 60 are quickly linearlyretracted to a neutral position, that is, with the point of needle 64retracted or withdrawn from the incision and within the housing 12 asshown in FIG. 5. Spring 34 is sized relative to housing 12 such thatwhen the holder 16 and control member 48 are in this neutral position,the spring 34 is at its free length position or neutral force position,that is, spring 34 is substantially neither in tension nor compression.

In moving from the retracted position of FIG. 1 to the skin penetratingposition shown in phantom in FIG. 5, it is primarily the inertia ormomentum of the moving holder 16 that causes the lancet to move distallypast the neutral position of the holder or free length position of thedistal end of spring 34 (position shown in full in FIG. 5). Since thedistal end of spring 34 is extended distally beyond the position itwould have when the spring 34 in its neutral or free length conditiondue primarily to the inertia of the moving holder 16, the spring istensioned and therefore swiftly retracts or moves the needle pointproximally from the piercing position back to the neutral position.

The parts may be proportioned such that the extent of distal travel ofthe lancet 60 may be limited by the engagement of the control member 48with a sidewall 74 (FIGS. 1, 5 and 6) of the slot 50, the indicatedphantom position of member 48 in FIG. 5, or, if desired, by theengagement of the upper end 66 of the lancet handle with the inner sideof the end wall of cap 24. In some cases, the construction may allow theend 66 to strike the skin.

The holder 16 and lancet holder 30 may be moved to a lancet access orunloading and loading position, the position shown in FIG. 6. This isaccomplished by removing cap 24 and urging the control member 48rightwardly against the bias force from its neutral position of FIG. 5and into an elongate slot portion 76 of slot 50, then longitudinally orlinearly upwardly and distally into an enlarged slot portion 78, andthen leftwardly into the access position in a recess 80 in slot 50 andwhich has a distally extending sidewall 82 holding the member 48 inplace. During this distal movement in slot portion 76 the coil spring 34is tensioned, that is, stretched beyond its neutral or free lengthcondition of FIG. 5. The tensioned spring 34 tends to maintain themember 48 urged downwardly in groove 80 so that it cannot move out ofthe groove.

In the lancet access condition of holder 16, as shown in FIG. 6, thelancet holding member 30 extends through and above the upper or distalopen end of the housing 12. In this position the upper portion of thelancet 60 may be grasped by the handle 62 and pulled upwardly to removeit from the member 30. A new lancet may then be inserted into the holder30 until it bottoms against the inner bottom wall of the member 30.After a new lancet is inserted into the holding member in the accessposition of FIG. 6, the needle sheath such as sheath 68 (FIG. 4) isremoved to expose the pointed needle tip, and then the external controlmember 48 is manually moved out of recess 80 into the enlarged slotportion 78. The member 48 is moved rightwardly against the rotary biasforce of spring 34 into an elongate slot 76 where the force of tensionedspring 34 swiftly moves the slide 28 proximally longitudinally oraxially of the housing so that it moves back into its neutral positionshown in FIG. 5, the bias force of the spring urging it against the leftedge 52 of the slot 50. The cap 24 may then be snapped back onto thedistal end of housing 12.

In use, a new lancet, such as lancet 60, is inserted into the lancetholder 30 when the control member 48 is positioned in the lancet accessposition indicated in FIG. 6. The needle sheath, such as sheath 68 (FIG.4) is removed from the lancet, and the control member 48 is manuallymoved out of recess 80 so that the tensioned spring 34 withdraws thelancet and slide 48 through slot portion 76 to the neutral positionindicated in FIG. 5. The cap 24 or a new cap may now be placed over thedistal end of the housing 12.

Next, the control member 48 is manually moved proximally or downwardlyin slot portion 72 compressing coil spring 34 and then over to recess 68to place the member 48 and holder 16 in a latched retracted or cockedposition as shown in FIGS. 1 and 2. The housing 12 may now be handgrasped and the end cap 24 pressed against the skin, such as the skin ofthe finger, of the person whose blood is to be tested. The controlmember 48 may now be forced out of the retracted position so that theforce of spring 34 and the inertia of the lancet 60 and lancet holder 16effect piercing of the skin by the needle tip of the lancet and quickremoval of the needle from the skin incision to the neutral position asindicated in FIG. 5. The cap 24 may now be removed and the controlmember 48 moved to the lancet access position as shown in FIG. 6 so thatthe used lancet may be easily and safely removed from the injector 10and discarded. At this time, a new lancet may be inserted into theholding member 30 and the control member again moved to the neutralposition of FIG. 5 so that the device is again ready to be used toeffect skin piercing.

The blood flow caused by the lancet piercing the skin may be collectedin a capillary tube or pipette and subjected to clinical testing. Forexample, at times, glucose testing may be done relatively often in thecase of diabetics. Also, such testing may be self-performed such as inthe home for monitoring blood glucose.

The lancet injector device 10 effects a very quick incision andwithdrawal of the lancet needle so that patient discomfort is minimized.Since the lancet is substantially hidden by the housing, one does notsee the lancet point during use and the anxiety of the patient isgenerally substantially less than where one sees the lancet point. Also,the injector 10 is easy to operate.

The injector 10 requires only one functional spring while operating in asimple and highly effective manner. The spring 34 is shown as a singlecoil propulsion compression spring which propels the lancet holder 16for the skin piercing operation. Spring 34 provides the force forpiercing the skin as well as swiftly withdrawing the lancet from theincision. The spring 34 is also tensioned when the device is in itslancet access position (FIG. 6) so that its force is also used toquickly withdraw the exposed lancet needle to the neutral position (FIG.5) when the control member 48 is moved accordingly. Also, spring 34provides the arcuate biasing force normally urging the slide 48leftwardly when such bias is employed in the device. The construction ofdevice 10 requires few moving parts and, in general, is simple andeconomical to make and use.

The housing 12, holder 16 and plug 20 may be economically molded fromany suitable plastic, for example, from a copolymer made fromacrylonitrile, butadiene, and styrene (ABS), or polypropylene. The cap24 may also be made from a suitable plastic such as polypropylene. Whilea snap-on type cap 24 is shown, other cap constructions allowingattachment and removal are possible.

As various changes could be made in the above construction withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description and apparatus shown in theaccompanying drawing shall be interpreted as illustrative and not in alimiting sense.

We claim:
 1. A lancet injector comprising an elongate housing having agenerally longitudinally extending slot in the sidewall thereof, alancet holder longitudinally slidable in said housing and adapted toreleaseably receive a lancet for piercing the skin, spring means in saidhousing having one end connected to said holder and the other endconnected to a proximal end portion of said housing, and a controlmember extending through said slot and connected to said holder formanually moving said holder, said control member being movable to movesaid holder linearly in a proximal direction against the force of saidspring means to a releasable retracted position thereby compressing saidspring means, said control member being movable to release said holderfrom said retracted position so that the force of said spring means andthe inertia of said holder during movement thereof moves said holderlinearly in a distal direction to a lancet piercing position in whichsaid spring means is tensioned so as to move said holder proximally fromsaid piercing position to a neutral position where said spring means isin a free length neutral force condition, said control member beingdistally movable to move said holder to a lancet access positiondistally beyond said lancet piercing position.
 2. The injector of claim1 wherein said slot includes a first recess for receiving said controlmember and holding it and said holder against the compressive force ofsaid spring means thereby latching said holder in the retractedposition, and a second recess for receiving said control member andholding it and said holder against the tension force of said springmeans for latching said holder in said lancet access position.
 3. Theinjector of claim 1 or 2 wherein the distal end of said holder isdistally beyond the distal end of said housing when said holder is insaid lancet access position.
 4. The injector of claim 1 or 2 whereinsaid spring means is a coil spring and the sole functional spring in theinjector.
 5. The injector of claim 1 or 2 wherein said slot includes alongitudinally extending slot portion connected at the proximal end withsaid first slot recess and having a wall at the distal end thereof, saidcontrol member being engageable with said wall to limit the distalmovement of said holder after release thereof from said retractedposition and define said lancet piercing position when said controlmember is engaged with said wall, said holder being movable from saidpiercing position to a neutral force position wherein said spring meansis in the free length neutral force condition and proximal of said wall.6. The injector of claim 5 wherein said slot includes a secondlongitudinally extending slot portion connected with said first namedslot portion and said second recess, and said spring means is arrangedto bias said holder in a rotary direction.
 7. A lancet injectorcomprising an elongate housing having an elongate chamber therein, alancet holder linearly slideable longitudinally in said chamber andadapted to hold a lancet, spring means in said chamber, a slot in thesidewall of said housing extending generally longitudinally of saidhousing and having first and second recesses, a control member connectedto said holder and extending through said slot to the exterior of saidhousing for manually moving said holder, said control member beingmovable to a latched retracted position into said first recess tothereby move said holder against the force of said spring means to aretracted position within said chamber wherein said spring means is incompression, said control member being movable from said latchedretracted position in said first recess so that the force of said springmeans effects linear distal movement of said holder and control memberlongitudinally to lancet skin piercing positions, said control memberbeing distally movable longitudinally in said slot distally beyond itsskin piercing position to a latched lancet access position in saidsecond recess wherein said spring means is in tension and said holder isheld against longitudinal movement by walls of said second recess andwherein said holder can be loaded with a lancet.
 8. The injector ofclaim 7 wherein said holder extends distally outwardly of the distal endof said housing when said control member is in access position.
 9. Theinjector of claim 7 or 8 wherein said spring means is fixedly secured atits opposite ends to said holder and a proximal end portion of saidhousing, respectively.
 10. A lancet injector comprising an elongatehousing, a lancet holder longitudinally slideable linearly in saidhousing and adapted to have a lancet releaseably connected thereto, acoil spring in said housing fixedly connected at one end to said holderand fixedly connected at the opposite end to a proximal end portion ofsaid housing, said housing having an opening through the sidewallthereof, a manually operated control member connected to said holder andextending through said opening to the exterior of said housing forcontrolling the movement of said holder, said housing opening havingsidewalls defining first and second longitudinally extending slots, saidfirst slot being connected to and extending distally beyond said secondslot, said second slot having a distal end wall, said sidewalls alsodefining a first recess disposed arcuately relative to said second slotand connected thereto, and a second recess adjacent the distal end ofsaid first slot and connected to and spaced arcuately relative thereto,said control member being in a neutral position proximally of saiddistal end wall of said second slot when said spring is in its neutralforce condition, said control member being movable proximally in saidsecond slot from said neutral position into said first recess to therebylatch said holder in a retracted position with said spring compressedand urging said control member in a distal direction toward said firstrecess, said holder being movable under the forces of said spring fromsaid retracted position in response to movement of said control memberfrom said first recess to momentarily move said holder from saidretracted position and said control member distally in said second slotto skin piercing positions in which the distal tip of a lancet whenconnected to said holder is moved distally of the distal end of saidhousing for piercing the skin of a patient when disposed adjacent thedistal end of the housing, said control member being movable distallybeyond said neutral position and engageable with said distal end wall ofsaid second slot to limit the distal movement of said holder, saidcontrol member being movable from said neutral position thereof distallyand linearly in said first slot and then into said second recess tothereby latch said holder in a lancet access position wherein a lancetmay be inserted and removed from said holder, said spring beingtensioned when said control member is in said second recess to urge saidcontrol member in a proximal direction towards said second recess. 11.The injector of claim 10 wherein said spring applies a rotary biasingforce against said holder, and said spring is the only functional springin the injector.
 12. The injector of claim 1, 2, 8 or 10 furtherincluding an end cap removably connectable to the distal end of saidhousing and having an opening for movement therethrough of a needlepoint of a lancet connected to said holder during a skin piercingoperation.
 13. The injector of claim 1, 2, 8 or 10 further including alancet having a handle and a needle point extending from the distal endof said handle, and wherein said holder includes a sleeve having an opendistal end for slidingly receiving said handle in frictional engagementwith the sidewalls of said sleeve.